Naomi (or Naomi wife of Elimelech) was Ruth's mother-in-law. She is mentioned in the book of Ruth.
Naomi was widowed sometime before her sons Mahlon and Chilion were married to Orpah and Ruth. Intitially, she told her two daughters in law to go out on their own to find new husbands, but relented when Ruth demonstrated her desire to stay close to her. Upon arriving at Bethlehem, some of the townsfolk exclaim "Could this be Naomi?" to which she responds that she must be called Mara, or bitter.
As Ruth's mother-in-law, she keeps the family line going by unintentionally bringing Ruth into contact with Boaz, who was a relative on her husbands side. The two arrived as the barley harvest was beginning, and she soon approves Ruth's request to head out and collect scraps behind the harvesters in the fields, which lands Ruth in one of Boaz's fields. Upon Ruth's return from the fields, she is surprised to see her large haul, and soon asks her to remain with Boaz's servant girls, claiming that in any other field she would have been in at least some danger. Sometime after the harvests end, she asks Ruth to clean herself up and head to Boaz for a reason she doesn't give her. Upon going there and fulfilling Naomi's request to "note where he is lying, to uncover his feet," and to do what he tells her to do, Boaz thanks her for her kindness, and promises that either another kinsmen-redeemer or him will marry her to continue the family line. Upon Ruth's return, Naomi assures Ruth that he will settle the matter on that day, which he does, eventually marrying Ruth and keeping the family line that leads to David.